A188408 Number of (7*n) X n binary arrays with rows in nonincreasing order, 7 ones in every column and no more than 2 ones in any row.

1, 1, 8, 154, 7340, 681460, 111200600, 29445929253, 11930327925108, 7061916086148812, 5884543061841730064, 6695191219474600587460, 10138670050730337096234992, 19996250425584243540741431296, 50416254105984511132422687541856, 159887463958073530310081258765881180

Offset: 0

Author

R. H. Hardin, Mar 30 2011

Keywords

• nonn

Comments

Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 7. - Andrew Howroyd, Apr 07 2020

Examples

			All solutions for 14X2
..1..1....1..1....1..1....1..1....1..1....1..1....1..0....1..1
..1..1....1..1....1..1....1..1....1..1....1..0....1..0....1..1
..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..1
..1..0....1..1....1..1....1..1....1..1....1..0....1..0....1..0
..1..0....1..0....1..1....1..1....1..1....1..0....1..0....1..0
..1..0....1..0....1..1....1..0....1..1....1..0....1..0....1..0
..1..0....1..0....1..0....1..0....1..1....1..0....1..0....1..0
..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1
..0..1....0..1....0..0....0..1....0..0....0..1....0..1....0..1
..0..1....0..1....0..0....0..0....0..0....0..1....0..1....0..1
..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..1
..0..1....0..0....0..0....0..0....0..0....0..1....0..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..1....0..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0
		

Crossrefs

Row 7 of A188403.

Extensions

a(0)=1 prepended and terms a(9) and beyond from Andrew Howroyd, Apr 06 2020